3 flats in converted house sharing supply.2 flats have water,I don't.Suspect airlock

[Unregistered]

Hello.

I live in a converted flat. I'm on the ground floor, and there is a basement and top floor.

The water supply comes in to the basement, then the pipe travels up to the ground floor where there are 2 stopcocks. 1 for the ground floor flat (mine). 1 for the top floor flat.

I turned my stopcock off this weekend to replace my washing machine taps (picture attached).

When I turned the stopcock back on, I had no water. However The top floor still receives water.

This has happened in the past. The solution has always been:

- Turn off the ground floor and top floor stopcock
- Turn off the stopcock in the basement
- Open the taps in my flat
- Turn on the ground floor stopcock
- Turn on the basement stopcock
- I get water

However this is no longer working.

I suspect this is due to an air lock in my pipes.

My hot water comes from a direct combination unit (see attached).

There isn't enough pressure from the hot water tap to try and force the hot water back through the cold water pipes to release the air lock.

Is it time to call a plumber?

Thanks

plumbing - Album on Imgur